The present invention relates to a cosmetic composition for skin care, which enhances the skin care effect of retinol and also alleviates the adverse effect thereof
Skin, which is the biggest organ of the human body, is composed of epidermis, dermis and subcutaneous fat. It performs various functions such as protection, barrier, temperature controlling, excretion and respiration. With the passage of time, however, those functions rapidly decline and a variety of changes occur to the skin. Physiological changes of the skin with aging, for example, include the decrease in thickness of epidermis, dermis and subcutaneous tissue; the dryness of skin resulting from the moisture reduction according to the changes of lipid composition and content in lipid barrier; and the occurrence of age spots, freckles, pigmentation or various skin lesions. Especially, the active oxygen species and free radicals, which can be generated by excess UV rays, air pollution, or fatigue or stress in modern life, oxidize or denature the bio-materials such as proteins, nucleic acids and membrane lipids, leading to the aging of the skin. Accordingly, there have been many studies on the occurrence of the wrinkles, age spots or freckles, the loss of skin elasticity, the pigmentation, and the dryness of skin.
A variety of cosmetic compositions have been developed in order to solve the problems with aging of the skin and some visible results have been obtained in improving skin wrinkles. Various clinical studies have been reported on the effects of cosmetic compositions containing retinoids in improving wrinkles, freckles and deposited pigments, especially of the compositions containing retinol (vitamin A) in improving wrinkles, sagging and the reduction in elasticity of skin formed by sunlight. Japanese Patent Laid-open Publication No. Hei 5-246838 discloses a method for improving wrinkles of skin by the synthesis of collagen. It teaches that the activity of collagenase that decomposes collagen to promote collagen metabolism might be reduced with aging, leading to the increase of cross-link collagens and the increase of skin wrinkles. U.S. Pat. Nos. 4,603,146 and 4,877,805 also disclose methods for improving skin wrinkles by using retinol that is effective in the synthesis of collagen and the inhibition from the decomposition thereof.
Retinol, an endogenous compound naturally present in the human body, is a lipo-soluble vitamin indispensable to the differentiation and growth of epithelial tissues. It is also believed to have an effect on the stimulation of physical growth and on the treatment of night blindness. In addition, when used in a cosmetic composition, retinol is believed to have an effect in enhancing the metabolism of skin cells, the differentiation and the resistance of the skin, and in inhibiting sebum secretion. Accordingly, there has been much interest in cosmetic compositions for skin care containing retinol. For example, various acne ointments containing retinol have been commercially available. Moreover, much effort has been invested in developing other uses of retinol, resulting in the application of retinol in treatment of UV damaged skin.
However, since retinol is extremely labile and thus easily oxidized and degenerated when exposed to air, vitamin A palmitate, a derivative of retinol, has been mainly used instead of retinol. But the recent tendency is back to the use of retinol itself because of the low stability and effect of vitamin A palmitate when applied to the skin. However, since the activity of retinol is rapidly decreased during storage, much research is still required in order to increase the shelf life of products containing retinol. At present, there has been research on encapsulating retinol with collagen, preventing retinol from air and light, or developing appropriate antioxidants.
Moreover, since retinol may cause skin irritation even with small doses, the use of retinol as an ingredient in cosmetics has been severely limited.
In the meantime, the Epidermal Growth Factor (EGF) is a strong promoter on the division of various epithelial cells originated in the ectoderm and mesoderm. It is extensively distributed in body fluid, especially in urine and breast milk (Carpenter, G. and Cohen, S., xe2x80x9cEpidermal growth factor,xe2x80x9d Ann. Rev. Biochem., 48, 192-216 (1979)). It is a single polypeptide consisting of 53 amino acid residues and has a molecular weight of 6,200 Daltons (Campion, S. R. and Niyogi, S. K., xe2x80x9cInteraction of epidermal growth factor with its receptorxe2x80x9d). In 1962, Cohen isolated EGF from the gland beneath the chin of the mature male mouse. In 1972, Savage and Taylor identified the primary structure of mouse EGF and the location of three intramolecular disulfide bonds in EGF that are essential for physiological function. Gregory demonstrated in 1975 that the human EGF (hEGF) is identical with Urogastron, an inhibitory hormone of gastric acid secretion extracted from the urine of pregnant women.
EGF is believed to have an excellent effect on skin injuries because it strongly promotes the proliferation of epithelial cells, endothelial cells and fibroblasts, and also the migration and proliferation of epithelial cells to where they are deficient.
It is an object of the present invention to provide a cosmetic composition for skin care, which enhances the effect of retinol, one of the conventional skin-care ingredients, and also alleviates the adverse effects of retinol. More specifically, it is an object of the present invention to provide a skin-care cosmetic composition, which enhances the effect of retinol such as the treatment of acne, the improvement of skin wrinkles, age spots, freckles, blotches or other pigmentation, and the moisturizing of skin, and also alleviates adverse effects of retinol such as skin irritation.
The present inventors have found that EGF remarkably enhances the effect of retinol used in topical therapeutics and cosmetics, and also effectively alleviates the skin irritation of retinol.
The present invention relates to a cosmetic composition for skin care containing retinol and EGF.
As used herein, xe2x80x98improving skin wrinklesxe2x80x99 means preventing, retarding, arresting, or even reversing skin wrinkles.
In the present invention, any human or nonhuman EGF, either natural or isolated from transformed microorganisms, can be used. Preferably, EGF isolated and purified from a recombinant E. coli (JM101) is used. In this case, EGF may be obtained by fermenting the recombinant E. coli for 48 to 72 hours according to the fed-batch method, and then isolating the fermented supernatant by Amberchrome CG71 chromatography and Q-sepharose chromatography (see U.S. Pat. No. 5,652,120; Japanese Patent No. 2,609,515; European Patent No. 652954; and Korean Patent Nos. 102993, 107023, 110123 and 114856). Furthermore, the above patents confirm that EGF isolated and purified from the recombinant E. coli is identical to the human EGF.
In the cosmetic composition of the present invention, EGF is preferably used in an amount of 0.00001 to 1% by weight, and more preferably, 0.0001 to 0.1% by weight based on the total weight of the cosmetic composition.
The amount of retinol used in the cosmetic composition of the present invention is preferably from 0.001 to 5.0% by weight, and more preferably 0.01 to 2.0% by weight based on the total weight of the cosmetic composition.
Examples of formulations of the cosmetic composition of the present invention include, but are not limited to, skin softener, astringent, nutrient emulsion, eye cream, nutrient cream, massage cream, cleansing cream, cleansing foam, cleansing water, powder, essence and facial pack.
In addition to retinol and EGF, other suitable ingredients can be added to the cosmetic composition of the present invention depending on the type of the cosmetic formulation or the purpose of the use.